Remove dead action pipeline: parsing, depth tracking, knowledge loop, fact miner

Agents now apply changes via tool calls (poc-memory write/link-add/etc)
during the LLM call. The old pipeline — where agents output WRITE_NODE/
LINK/REFINE text, which was parsed and applied separately — is dead code.

Removed:
- Action/ActionKind/Confidence types and all parse_* functions
- DepthDb, depth tracking, confidence gating
- apply_action, stamp_content, has_edge
- NamingResolution, resolve_naming and related naming agent code
- KnowledgeLoopConfig, CycleResult, GraphMetrics, convergence checking
- run_knowledge_loop, run_cycle, check_convergence
- apply_consolidation (old report re-processing)
- fact_mine.rs (folded into observation agent)
- resolve_action_names

Simplified:
- AgentResult no longer carries actions/no_ops
- run_and_apply_with_log just runs the agent
- consolidate_full simplified action tracking

-1364 lines.

poc-memory/src/lib.rs

@@ -31,7 +31,7 @@ pub mod tui;
 // Re-export agent submodules at crate root for backwards compatibility
 pub use agents::{
     llm, audit, consolidate, knowledge,
-    enrich, fact_mine, digest, daemon,
+    enrich, digest, daemon,
 };
 
 pub mod memory_capnp {